My house was completely rewired by the previous owner. They tore out all the old knob-and-tube and replaced it with modern wiring. I definitely appreciate this, but unfortunately they left absolutely no extra space on the new breaker box. Every single slot is filled with a circuit breaker.

6 Answers 6

There are caveats with both routes. When using tandem breakers on a 120 volt system (i.e. with a neutral present), you want to avoid something that is called a multifeed. This is, two circuits on the same phase sharing the same neutral. When using tandem breakers, its very easy to inadvertently do this.

If you are in the US, you will see two feeders from the meter, one of them probably has some red tape on it, the other is black. These are your phases. Normally, every other breaker is on a different phase, but tandem breakers put both circuits on the same. Take care that both circuits attached to a tandem have their own neutral (white wire).

While you might be able to install a tandem breaker yourself (I highly recommend calling a qualified professional), you will surely want an electrician to install a sub panel. They aren''ll want to be careful about where you place the breaker that feeds a sub panel, so that you don''t want a 100 amp sub panel breaker right in the middle of a water heater and an air conditioner.

In some countries it's illegal to do your own electrical work unless you're a qualified electrician. Some countries allow minor changes to be done to but not in the breaker or meter box. If anything goes wrong (your insurance may not cover you). I'd call in an electrician for this work. – MattJul 11 ''13 at 22:25

Woodworking Planshow to Woodworking Plans for Yeah, a service 'heavy up' would also be a good option here. – Tim Post♦Dec 8 ''17 at 20:29

Woodworking Planshow to Woodworking Plans for The only reason to replace the entire box is if aesthetics: if there isn''t physical space.

Putting in a new breaker box is much easier than replacing an entire box. If you replace the entire box, you will need to rewire every breaker. When the original box was wired there was lots of slack on each wire, but after each breaker was installed the wires would have been trimmed. A good electrician will allow slack in the wires for reconfiguring breakers, etc. but if it''t as neat or professional as it should be.

With a new box, on the other hand, you only need to remove one 220V or two adjacent 110V breakers. The old wires can be run into a junction box to provide as much length as you need for wiring into the new box.

As Mike Sherov noted, you need to be sure that your service can handle the load and number of circuits. That''d be surprised if the old service (probably 50 or 60 amp) wasn''re too busy for such questions.) Or you can research it yourself: it''10 at 16:33

Excellent point about wire slack. Sadly, whoever rewired the house left very little slack in any of the lines. It's been a total pain in the ass every time I've had to splice into an existing circuit. It sounds like adding a second box is the best way to go. If I go that route, are there more power limitations on the second box? – bengineerdWoodworking Planshow to Woodworking Plans for Jul 22 ''10 at 2:12

You can use a 100 amp sub panel and feed it with a 40, 60, 80 or 100 amp breaker from the main using a larger sub would provide for more spaces and not run into the current problem again as long as the main panel can handle the additional load. – Ed BealFeb 8 ''re already getting. Most of the time, the number of circuits in your breaker box corresponds to the level of service you''d recommend getting an electrician for this to calculate your energy needs.

However, if the 1 last update 2020/06/07 you know you have adequate power, and you''re using parts that are specified as appropriate by the manufacturer. However, if you know you the 1 last update 07 Jun 2020 have adequate power, and you''re using parts that are specified as appropriate by the manufacturer.

Feb 8 ''re already getting. Most of the time, the number of circuits in your breaker box corresponds to the level of service you''d recommend getting an electrician for this to calculate your energy needs.

However, if the 1 last update 2020/06/07 you know you have adequate power, and you''re using parts that are specified as appropriate by the manufacturer. However, if you know you have adequate power, and you''re using parts that are specified as appropriate by the manufacturer.

1) Code applies to everyone, not just licensed electricians. 2) Tandem capable panels will account for this in their panel rating (a type BR, for instance, will be listed and diagrammed as say, a 16/32 slot panel indicating it can take 16 full width breakers or 32 circuits worth of tandem/quadruplex breakers). – ThreePhaseEelWoodworking Planshow to Woodworking Plans for Dec the 1 last update 2020/06/07 8 ''14 at 23:34Dec 8 ''14 at 23:34

This couldn't be more wrong. If you add up the breakers in any panel, the amperage will likely exceed the service size. Sub panels don't themselves cause stress on the main circuit breaker. Assuming load is properly factored, there is no reason you would need an emergency service upgrade. – StevenWoodworking Planshow to Woodworking Plans for Jan 23 ''StackExchange.switchMobile("")' class="" data-gps-track="">Mobile